AXLE DRIVING APPARATUS

Description

Field of the Invention

[0001] The present invention relates to an axle driving apparatus for improving the straightforward running capacity of a vehicle on a muddy road or the like, and more particularly to an axle driving apparatus which is integrally provided with a hydrostatic transmission (hereinafter referred to as the HST); axles; a power transmitting mechanism, which can easily change the speed of the HST; an oil reservoir, which can absorb an increase in the volume of oil due to an increase in the temperature of the HST; and a differential locking device, all of which are provided in a single housing.

Background of the Invention

[0002] Conventionally, an axle driving apparatus consists of a housing for an HST, axles and a power transmitting device for interconnecting the HST and axles. On the center section of the HST is disposed a hydraulic pump, provided with a vertical input shaft, and a hydraulic motor, provided with a horizontal output shaft. A plurality of pistons are disposed in the hydraulic pump cylinder block. The heads of the pistons abut against a movable swash plate. Changing the angle of the movable swash plate changes the pump capacity so as to increase or decrease the number of rotations of the hydraulic motor. The movable swash plate is slanted, thereby enabling the speed of the HST to be changed by rotatably operating trunnions supported in the housing. Each trunnion is disposed on a longitudinally slanted axis of the swash plate, as disclosed in U.S. Patent No. 5,456,068, for example, which discloses the features of the preamble of claim 1.

[0003] A speed change controller, such as a pedal or a lever, which is provided on the vehicle can be operated normally longitudinally thereof so that its motion can be transmitted to a control arm of the axle driving apparatus through a link mechanism, such as a rod, disposed longitudinally of the vehicle. Hence, it is preferable that the control arm swing longitudinally around the lateral axis. One conventional construction is provided with a vertical operating shaft, independent of the trunnions, where both trunnions and the vertical operating shaft interlock with each other. The control arm is provided at one end of the operating shaft so that the control arm swings longitudinally around the vertical axis, and the other end is constructed so that the trunnion projects at the axial end thereof from the front wall of the housing. A control arm is provided at the axial end so that the control arm swings laterally around the longitudinal axis. A complex linkage mechanism, with respect to the vertical operating shaft and trunnions, is required in the first construction described above, thereby increasing the number of parts and assembly time, making the axle driving apparatus too expensive to produce. The second construction described above requires a separate link mechanism for converting the longitudinal motion into a lateral motion, thereby requiring space to provide two link mechanisms in the vehicle, making it difficult to apply the apparatus to a vehicle of small size and increasing the number of parts required.

[0004] U.S. Patent Nos. 5,440,951 and 5,515,747 disclose that when the HST and the mechanism for transmitting power to the axles from the HST are housed in the same housing, the housing can be filled with oil to be used as both operating oil for the HST and lubricating oil for the transmitting mechanism. In this case, a foreign object, such as iron powder, created by the rubbing of the transmitting mechanism may flow toward the HST. The iron powder or other foreign object is removed by an oil filter so as not to enter into the HST closed fluid circuit. However, the iron powder or the like may encroach on the piston and swash plate and thereby adversely affect them. The housing is integrated in part with the oil reservoir so as to enable the oil volume in the housing to be adjusted when expanded due to a rise in temperature. However, the greater the quantity of oil, the larger the increase in volume. Thus, the housing must be made larger and the reservoir therefore becomes larger so that the housing itself has to be large in size.

[0005] U. S. Patent No. 5,094,077 discloses that in order to prevent the speed change controller equipped on the vehicle from being hastily operated by an operator, a shock absorber is provided on the control arm. The shock absorber should be disposed above the upper wall of the housing because the control arm is configured to vertically and longitudinally swing around the axis on the upper wall of the housing. Therefore, space for disposing the shock absorber without interference with an input pulley or an enlarged portion of the upper wall of the housing is required.

[0006] Further, where a differential gear is provided between the left and right axles, when one axle is idling, a driving force cannot be transmitted to the other axle. Hence, it is desired to provide a differential locking device on the axle driving apparatus for integrating the differential locking device with the HST and the axles.

Summary of the Invention

[0007] The invention provides an axle driving apparatus for a vehicle as defined in claim 1. Preferred embodiments are defined in the dependent claims.

[0008] In a preferred embodiment the axle driving apparatus of the present invention is partitioned by an internal wall provided within the housing, into a first chamber for housing therein the HST and a second chamber for housing therein axles and a transmitting mechanism which transmits power from an output shaft of the HST to the axles. Both chambers are filled with common oil. An oil filter is disposed therebetween to allow the chambers to communicate with each other. One chamber communicates with an oil reservoir. Trunnions for the swash plate to change the output rotation of the HST are supported between the internal wall and a side plate fixed to the housing. The trunnions are disposed laterally of and in parallel to the axles. One of the trunnions projects outwardly from the housing so as to fix an arm. The shock absorber is connected thereto, thereby preventing hasty speed change. A differential locking device is attached to a differential gear differentially connecting the left and right axles. During the normal running of the vehicle, the differential rotation can be performed. When one axle is idling, both axles are adapted to be directly connected to each other.

[0009] These and other objects of the invention will become more apparent from the detailed description and examples which follow.

Brief Description of the Figures

[0010] 

Fig. 1 is a plan view of an axle driving apparatus;

Fig. 2 is a partially sectional plan view of the same in which an upper half housing thereof is removed;

Fig. 3 is a sectional view looking in the direction of arrows 3-3 in Fig. 2;

Fig. 4 is a sectional view looking in the direction of arrows 4-4 in Fig. 2;

Fig. 5 is a sectional view looking in the direction of arrows 5-5 in Fig. 2;

Fig. 6 is a sectional view looking in the direction of arrows 6-6- in Fig. 2;

Fig. 7 is a sectional view looking in the direction of arrows 7-7 in Fig. 2;

Fig. 8 is an enlarged sectional plan view of a principal portion of the mechanism of a braking device;

Fig. 9 is an enlarged sectional side view of a principal portion of the same;

Fig. 10 is a enlarged sectional view of only a part of a principal portion of the same;

Fig. 11 is a left side view of a center section of the present invention;

Fig. 12 is a plan view of the same;

Fig. 13 is a sectional view looking in the direction of arrows 13-13 in Fig. 11;

Fig. 14 a sectional view looking in the direction of arrows 14-14 in Fig. 11;

Fig. 15 is a sectional view looking in the direction of arrows 15-15 in Fig. 11;

Fig. 16 is a sectional view looking in the direction of arrows 16-16 in Fig. 12;

Fig. 17 is a sectional view looking in the direction of the arrows 17-17 in Fig. 12;

Fig. 18 is a sectional view looking in the direction of the arrows 18-18 in Fig. 12;

Fig. 19 is a sectional view looking in the direction of the arrows 19-19 in Fig. 12;

Fig. 20 is a sectional view looking in the direction of the arrows 20-20 in Fig. 12;

Fig. 21 is a bottom plan view of the center section from which the charge pump has been removed;

Fig. 22 is sectional view of a differential gear and a differential locking device;

Fig. 23 is a side view of a slider of the differential locking device;

Fig. 24 is a side view of a ring gear of the same; and

Fig. 25 is a perspective exploded view of the differential gear of the present invention.

Detailed Description of the Preferred Embodiments

[0011] Figs. 1 - 7 show the construction of an axle driving apparatus. The housing of the axle driving apparatus comprises an upper half housing 1 and a lower half housing 2 joined to each other along a horizontal, flat joint surface along the periphery of the upper and lower half housings 1,2. A bearing for a motor shaft 4 is provided on the joint surfaces of both upper half housing 1 and lower half housing 2. Bearings for axles 7 are shifted upwardly from the joint surface of both upper half housing 1 and lower half housing 2 and are disposed in upper half housing 1 to rotatably support axles 7. Axles 7 are differentially connected by a differential gear unit 23 and project laterally outwardly of the housing.

[0012] The interior of the housing is partitioned by an internal wall 8 into a first chamber R1 for housing therein an HST and a second chamber R2 for housing therein a gear-type drive train which transmits power to differential gear unit 23 from motor shaft 4 to axles 7. First chamber R1 and second chamber R2 are filled with common oil which forms an oil sump. As shown in Fig. 7, an oil feed lid 6 is provided on an upper wall of upper half housing 1 above differential gear unit 23. The housing can be filled with operating oil through lid 6. As shown in Fig. 6, an oil flow port 75 is provided in the upper portion of upper half housing 1. Upper half housing 1 communicates through a piping 9, of rubber hose or the like, with the interior of an oil reservoir 10 mounted at a predetermined position on the vehicle, thereby enabling the volume of operating oil in oil reservoir 10 to be adjusted.

[0013] As shown in Fig. 6, an oil bore 8a is open at a predetermined position in internal wall 8 which partitions first chamber R1 from second chamber R2. An oil filter 18 covers oil bore 8a. In this embodiment, as shown in Figs. 2 and 6, oil bore 8a and oil filter 18 are disposed on internal wall 8 between the portion containing the HST and the portion containing the right side axle 7, thereby enabling oil to flow between first chamber R1 and second chamber R2 through oil filter 18. Accordingly, oil filling the housing can be used as both operating oil for the HST and lubricating oil for the gears and bearings. When the oil enters into first chamber R1 from second chamber R2, foreign objects such as iron powder which are harmful to the HST, are filtered by oil filter 18.

[0014] Internal wall 8 is provided within the housing so that first chamber R1 is disposed in front of axles 7 and to the side of the drive train for transmitting power from motor shaft 4 to differential gear unit 23. Internal wall 8, as shown in Fig. 4, comprises (1) an internal wall portion 1a erected integrally with the upper inner surface of upper half housing 1 and is positioned at the end surface on the same plane as the joint surface of the housing parts 1, 2 and (2) an internal wall portion 2a erected integrally with the inner bottom surface of lower half housing 2 and positioned at the end surface on the same plane as the joint surface of the housing. When both upper half housing 1 and lower half housing 2 are joined together, the end surfaces of both internal wall portion 1a and internal wall portion 2a join each other to form internal wall 8, thereby partitioning the interior of the housing into first chamber R1 and second chamber R2.

[0015] The HST is housed in first chamber R1. The HST comprises a hydraulic pump P, a hydraulic motor M and a center section 5. Center section 5 is elongated and is longitudinally disposed in first chamber R1. A vertical surface 91 is formed at the front of center section 5 on which hydraulic motor M is disposed. A horizontal surface 90 is formed along the top of center section 5 on which hydraulic pump P is disposed. A pump shaft 3 is substantially vertically disposed on center portion 5 and is positioned between motor shaft 4 and axles 7 which extend substantially horizontally and in parallel to each other. A pump mounting surface 40 is formed on horizontal surface 90 of center section 5 for hydraulic pump P. A cylinder block 16 is rotatably and slidably disposed on pump mounting surface 40. Pistons 12 are fitted into a plurality of cylinder bores in cylinder block 16 and are reciprocally movable by biasing springs. The heads of pistons 12 abut against a thrust bearing 11a held to the movable swash plate 11. At the center of movable swash plate 11, an opening 11 b is provided through which pump shaft 3 perforates. Pump shaft 3, used also as an input shaft, is disposed on the rotary axis of cylinder block 16 and is fixed thereto as that pump shaft 3 and cylinder block 16 rotate together. Pump shaft 3 projects at the upper axial end thereof outwardly from the upper wall of upper half housing 1. An input pulley 43 with a cooling fan 44 is fixed to pump shaft 3. Input pulley 43 is given power from a prime mover (not shown) through a belt transmitting mechanism (not shown).

[0016] As seen in Fig. 6, the piston abutting surface of movable swash plate 11 is disposed perpendicular to the rotary axis of cylinder block 16. Movable swash plate 11 is shown in the neutral position. Movable swash plate 11 can be tilted from side to side so as to enable the discharge amount and discharge direction of oil from hydraulic pump P to be changed. As seen in Figure 4, for example, movable swash plate 11 is integrally provided with trunnions 35L and 35R, which project laterally from both sides of swash plate 11 and are disposed in parallel to axles 7. Movable swash plate 11, as shown in Figs. 2 and 4, is slantingly rotatably supported between the two parallel walls of internal wall portion 1a in upper half housing 1 and the side wall of the upper half housing 1. A recess 1 b is bored in the side surface of internal wall portion 1a. Recess 16 has an inner diameter about equal to the outer diameter of a bearing bush fitted on trunnion 35L. As best seen in Figure 4, trunnion 35L is rotatably supported in recess 1b. In order to bore recess 1b in internal wall portion 1a, an opening 1c is formed in the side wall of upper half housing 1. A machining tool for boring recess 1b is inserted into upper half housing 1 through opening 1c. A side plate 15 for closing opening 1 c is detachably fixed onto the outer surface of the side wall of upper half housing 1 through sealing members (not shown). Trunnion 35R extends into a hollow cylindrical portion integrally formed in side plate 15 so as to be rotatably supported therein. Movable swash plate 11 is longitudinally tilted around trunnions 35L and 35R within first chamber R1, enabling the output of hydraulic pump P to be changed.

[0017] At the outer surface of side plate 15, a plurality of fins 15a (see Fig. 3) for receiving cooling wind from cooling fan 44 are disposed in the direction of the flow of the cooling wind. Wind blowing across fins 15a lowers the temperature of oil stored in first chamber R1.

[0018] The axial end of trunnion 35R projects outwardly from side plate 15. A control arm 38 (discussed below) is fixed onto the axial end and is connected through a link or wire (not shown), to a speed change lever mounted at the driver's seat of the vehicle, so as to rotate around the lateral axis of the vehicle body. This simplifies the transmitting mechanism for slantwise control of movable swash plate 11. A neutral return coiled spring 31 is fitted onto trunnion 35R in first chamber R1. Both ends of neutral return coiled spring 31 project forwardly between an engaging pin 39 and around an eccentric shaft 33 mounted onto the inner surface of side plate 15 (see Figure 2). Engaging pin 39 projects from an arm 11d which projects forwardly from movable swash plate 11.

[0019] Accordingly, when control arm 38 is rotated in order to change the speed of the vehicle, arm 11d rotates together therewith and one end of neutral return coiled spring 31 moves away from the other end toward engaging pin 39. The other end of neutral return coiled spring 31 is retained by eccentric shaft 33 so as to apply a biasing force to control arm 38 which tends to return to the neutral position. When the operating force to the speed change lever is released, the restoring force created at one end of neutral return coiled spring 31 returns engaging pin 39 toward eccentric shaft 33 so as to be held in a neutral position. A portion of eccentric shaft 33 extending outwardly from side plate 15 is fixed thereto through an adjusting nut 33a, which can be released to properly rotatably shift eccentric shaft 33, thereby shifting arm 11d around trunnion 35R through neutral return coiled spring 31. This enables movable swash plate 11 to be adjusted to the accurate neutral position.

[0020] Control arm 38 is fixed to the end of trunnion 35R which extends outside of the housing, as shown in Fig. 3. Control arm 38 is substantially V-shaped, with a first retaining portion 38a and a second retaining portion 38b. First retaining portion 38a projects upwardly to connect with a speed changing member such as a lever or pedal (not shown), and with trunnion 35R when the speed change force is applied. Second retaining portion 38b projects slantwise rearwardly of the vehicle to connect with one end of a movable portion 73a of a shock absorber 73. Shock absorber 73 and control arm 38 are formed to straddle right axle 7. The base of a fixed portion 73b of shock absorber 73 is pivotally supported to a mounting pin 74b. Mounting Pin 74b is mounted to the rear end of a support plate 74 fixed through mounting bolts 74a to the lower surface of a sleeve for right axle 7. Thus, shock absorber 73 connects with control arm 38 so as to prevent a rapid speed change operation. Further, the operating force of the speed changing member, when released, does not rapidly return swash plate 11 to its neutral position, due to the spring force of neutral return coiled spring 31. This prevents an abrupt stop of the vehicle caused by the braking action of the HST.

[0021] Because shock absorber 73 is disposed longitudinally along one side of the housing, it is not necessary to consider the height of input pulley 43 or an enlarged portion of the housing. A reasonable connection and arrangement is provided allowing control arm 38 to be swung along a lateral axis of the apparatus.

[0022] Pressure oil from hydraulic pump P is sent to hydraulic motor M through an oil passage in center section 5. Hydraulic motor M, as shown in Fig. 5, is constructed so that a motor mounting surface 41 is formed along vertical surface 91 of center section 5. A cylinder block 17 is rotatably slidably mounted to motor mounting surface 41. A plurality of pistons 13 are reciprocally movably inserted into a plurality of cylinder bores in cylinder block 17 through biasing springs. A thrust bearing, held to a fixed swash plate 37, abuts against the heads of pistons 13. Fixed swash plate 37 is fixedly positioned between upper half housing 1 and lower half housing 2. Motor shaft 4 is disposed on the rotary axis of cylinder block 17 and is fixed thereto so that motor shaft 4 and cylinder block 17 move together. One end of motor shaft 4 is supported in a shaft bore provided at the center of motor mounting surface 41 of center section 5. The other end of motor shaft 4 perforates through internal wall 8, formed at the joint surface of upper half housing 1 and lower half housing 2, so as to enter into second chamber 2. Motor shaft 4 is rotatably supported by a bearing 76 fitted into internal wall 8. Bearing 76 includes an oil-tight seal in order to partition first chamber R1 and second chamber R2. In particular, an O-ring 77 is provided on the outer periphery of bearing 76.

[0023] A brake disc 19 is fixed to one axial end of motor shaft 4 positioned in second chamber R2. As shown in Fig. 9 a brake pad 98 is fitted into the inner surface of upper half housing 1 positioned at one side of the upper portion of brake disc 19. At the opposite side of brake disc 19, a brake operating shaft 97 is supported which perforates the wall of upper half housing 1 from the outside to the inside thereof through a support plate 92. Brake pad 98 and the end surface of brake operating shaft 97 are opposite to each other. Brake disc 19 is sandwiched therebetween. Brake operating shaft 97 is supported in parallel to motor shaft 4. A brake arm 93 is fixed to the end of brake operating shaft 97 outside of the housing. A spring 94 is fitted onto brake operating shaft 97 between brake arm 93 and support plate 92, so as to bias the end surface of brake operating shaft 97 away from brake disc 19.

[0024] A flange 97a is formed within the housing at one end of brake operating shaft 97. A plurality (four in this embodiment) of groves 97b are provided at the surface of flange 97a facing the inner surface of the housing. Cam grooves 92a, each V-shaped in cross-section and arcuate when viewed in plan are provided at the end surface of support plate 92, opposite to grooves 97b. As shown in Fig. 10, balls 95 are interposed between cam grooves 92a and grooves 97b. In such construction, when brake arm 93 is rotated, brake operating shaft 97 rotates along its longitudinal axis. Balls 95, held by recesses 97b, slowly ride onto the shallowest portions of cam groove 92a from the deepest portions thereof. This causes brake operating shaft 97 to slidably move, due to the thrust generated thereon by balls 95, toward brake disc 19 thereby sandwiching brake disc 19 between brake pad 98 and the end surface of brake operating shaft 97 so as to brake motor shaft 4. Flanges 92b, which extend radially and are V-shaped, are integrally provided at the outer end of support plate 92 (see Figure 8). Elongate slots 92c, which are oval-arcuate shaped are open in flanges 92b around brake operating shaft 97. Bolts 96 are inserted into elongate slots 92c, thereby fixing support plate 92 onto the outer surface of the side wall of upper half housing 1. Bolts 96 may be unscrewed to properly rotate flanges 92b around brake operating shaft 97, thereby enabling balls 95 to adjust the length of time during which balls 95 ride on cam groove 97b.

[0025] Next, explanation will be given on the construction of center section 5 for loading thereon hydraulic pump P and hydraulic motor M in accordance with Figs. 11 through 21. Center section 5 is longitudinally elongated and is provided at one side thereof with a bolt bore 5h and at another side thereof with two bolt bores 5h. Three mounting bolts are inserted into bolt bores 5h and are used to fix center section 5 to the inner wall of upper half housing 1 in first chamber R 1. At the center of pump mounting surface 40 and at the rear and upper surface of upper half housing 1 is formed a bearing bore for rotatably supporting the lower end of pump shaft 3. A pair of arcuate ports 40a and 40b are open longitudinally through center section 5 around a bearing bore. Feed or discharge oil is communicated with cylinder block 16 through parts 40a and 40b. At the center of motor mounting surface 41, vertically disposed in front of pump mounting surface 40, is bored a bearing bore for rotatably supporting one end of motor shaft 4. A pair of arcuate ports 41 a and 41 b are open vertically and around the bearing bore, thereby communicating feed or discharge oil with cylinder block 17.

[0026] In order to connect arcuate ports 40a and 40b at pump mounting surface 40 with arcuate ports 41a and 41b at motor mounting surface 41, a first linear oil passage 5a and a second linear oil passage 5b are bored in a thick portion of center section 5, in parallel to each other. As shown in Fig. 12, the center of pump mounting surface 40 is positioned along an imaginary vertical plane (line 16 - 16) disposed along motor mounting surface 41. Half of cylinder block 16 mounted on pump mounting surface 40 (as shown in Fig. 2) overlaps, when viewed from above, with half of cylinder block 17 disposed on motor mounting surface 41. This arrangement permits the HST and first chamber R1 which contains the HST to be smaller in lateral width. A third linear oil passage 5c communicates horizontally and perpendicularly with an intermediate portion of second oil passage 5b. Arcuate port 40a at pump mounting surface 40, as shown in Fig. 18, is shallow and directly communicates with first oil passage 5a. Arcuate port 40b is deeper to communicate with third oil passage 5c. Arcuate port 41 a at motor mounting surface 41 is deeper at the upper portion thereof to communicate with first oil passage 5a and shallow at the lower portion thereof, as shown in Figs. 16 and 17. Arcuate port 41b communicates, at the lower portion thereof, with second oil passage 5b. Thus, first oil passage 5a communicates with arcuate port 40a and with arcuate port 41a, while second oil passage 5b and third oil passage 5c communicate with arcuate port 40b and with arcuate port 41b, so as to form a closed fluid circuit in center section 5.

[0027] With reference to Figure 17, check valves 54 and 55 are disposed at the open ends of first oil passage 5a and second oil passage 5b respectively. Both first oil passage 5a and second oil passage 5b are closed by plug members 64a in which check valves 54 and 55 are disposed, respectively. The open end of third oil passage 5c is closed by a plug member 64b. Check valves 54 and 55 communicate at the inlet sides thereof with oil passage 5d through oil bores 54b and 55b provided at casings 54a and 55a. The open end of oil passage 5d is positioned in a recess 5g formed at the lower surface of center section 5. At the lower surface of center section 5, opposite to pump mounting surface 40, a charge pump casing 46 is mounted through a plurality of mounting bolts 69. A trochoid-type charge pump 45 is housed (see Figure 4) in a recess formed at a center of the upper surface of charge pump casing 46. Trochoid-type charge pump 45 is provided with internal teeth and external teeth. The lower end of pump shaft 3 projects downwardly from center section 5 and engages with the external teeth so as to drive charge pump 45. Charge pump 45, however, may be of an external gear type or other known type.

[0028] As seen in Figures 18 and 19, charge pump 45 has a discharge port 45a and an intake port 45b. Intake port 45b communicates with an opening 46b (Figure 17) into which the open end of a cylindrical oil filter 56 is inserted (see Figs. 5 and 6). Oil filter 56 is disposed under hydraulic motor M in first chamber R1. Oil filter 56 is insertable into charge pump casing 46 which is in the housing from the exterior thereof through an insertion bore open at the front wall of lower half housing 2. Oil filter 56 is interposed between charge pump casing 46 and a plug member 48 which closes the insertion bore at the front wall of lower half housing 2. Plug member 48 can be removed to facilitate maintenance and inspection of oil filter 56. A pair of oil joints 49 and 50 project from the a side surface of charge pump casing 46 (Figure 13). The ends of joints 49 and 50, as shown in Fig. 3, are exposed at a lower portion of the outside surface of lower half housing 2. Oil joints 49 and 50 function as an oil pressure source for hydraulic actuators equipped outside of the vehicle.

[0029] Oil joint 50 is formed to serve as an oil takeout port and communicates with discharge port 45a of charge pump 45 through an oil passage 46a as shown in Fig. 13. A first relief valve 57, for setting the oil pressure of discharge port 45a. is housed in charge pump casing 46 and is connected to an oil passage 46c which is branched from oil passage 46a. Relief oil discharged from first relief valve 57 flows into recess 5g at the lower surface of center section 5 through oil passage 46c. Oil joint 49 is formed to be an oil return port and to communicate with recess 59 of center section 5 through oil passages 46d and 46e. A second relief valve 58 for setting the oil pressure in recess 5g to be supplied to the closed circuit of the HST is housed in charge pump casing 46 and connects with recess 5g through an oil passage 46f. Relief oil discharged from second relief valve 58 is discharged outwardly from charge pump casing 46 through an oil passage 46g.

[0030] As seen in Figure 17, when charge pump 45 is driven, oil flowing into recess 5g through the oil passage 46c is adjusted by second relief valve 58. This causes check valve 54 or 55 to open through oil passage 5d at the low pressure side of one of oil passages 5a. 5b or 5c, thereby forcibly supplying operating oil into the closed fluid circuit for the HST.

[0031] When the vehicle is stopped on a sloping surface, and the HST is put in the neutral position without the parking brake exerted, the force causing the driving wheels of the vehicle to roll acts on the closed fluid circuit of the HST to generate pressure so as to cause negative pressure in the closed fluid circuit and possibly causing the vehicle to move. In order to prevent such a phenomenon, a check valve 47 (see Fig. 15) is housed in charge pump casing 46 which can supply operating oil to the closed fluid circuit of the HST even when charge pump 45 is not driven. Check valve 47 communicates at the inlet side thereof with intake port 45b through an oil passage 46h and at the outlet side with recess 5g through an oil passage 46i. When charge pump 45 is driven to flow operating oil into recess 5g though oil passages 46c and 46e, check valve 47 closes between oil passage 46h and oil passage 46i. When charge pump 45 is not driven, causing negative pressure on the low pressure side of the closed circuit, check valve 47 is open to enable oil filtered by filter 56 to be guided from intake port 45b and oil passages 46h and 46i into recess 5g. Check valve 54 or 55, at the negative pressure side of the closed fluid circuit, is open through oil passage 5d, whereby oil is supplied to the closed fluid circuit. Thus, oil can be maintained in the closed fluid circuit at all times.

[0032] In order to place operating oil into the closed fluid circuit after the axle driving apparatus is assembled, oiling pipes 52 and 53 are disposed at the lower surface of center section 5 as shown in Figs. 11, 15, 17 and 20. At the lower surface of center section 5, a fourth vertical passage 5e is bored to communicate with the upper deep portion of arcuate port 41a. A fifth vertical oil passage 5f is bored to communicate with second oil passage 5b. Oiling pipes 52 and 53 are mounted into oil passages 5e and 5f respectively and are opened at the lower ends thereof outwardly from the bottom wall of lower half housing 2 and closed at the open ends by use of plug members after the closed fluid circuit is filled with operating oil.

[0033] As shown in Figs. 2 and 5, a by-pass arm 60 for opening the interior of the closed circuit to the oil sump, in order to enable the axle to be idle during hauling of the vehicle, is disposed in the upper portion of upper half housing 1. In particular, by-pass arm 60 is fixed at its base onto the upper end of a by-pass shaft 61, which is vertically, rotatably and pivotally supported to the upper wall of upper half housing 1. By-pass shaft 61 extends at its lower end into a thick portion of motor mounting portion 41 of center section 5. A flat surface 61a is formed at a part of the outer periphery of the lower end of by-pass shaft 61. A through-bore 5i (see Fig. 11) is open at motor mounting surface 41 of center section 5 slightly above the center thereof and between arcuate port 41 a and 41 b. A push pin 62 (see Fig. 5) is slidably supported into through-bore 5i along the rotary axis of cylinder block 17. One end surface of push pin 62 can abut against the rotary sliding surface of cylinder block 17 in close contact with the motor mounting surface 41. The other end surface abuts against flat surface 61 a of by-pass shaft 61.

[0034] Thus, when an operator operates a by-pass operating lever (not shown) equipped on the vehicle when the vehicle is hauled, by-pass shaft 61 is rotated through by-pass arm 60. Push pin 62 is pushed toward cylinder block 17 by the flat surface of the lower end of by-pass shaft 61. Push pin 62 moves the cylinder block 17 above motor mounting surface 41. First oil passage 5a and second oil passage 5b communicate with the oil sump of the housing through arcuate ports 41 a and 41b respectively, thereby enabling motor shaft 4 to freely rotate.

[0035] As shown in Figs. 2 and 7, the drive train for transmitting power from motor shaft 4 to differential gear 23 is constructed with a gear 25 provided on a portion of motor shaft 4 entering into second chamber R2, for engaging with a larger diameter gear 24, fixed onto a counter shaft 26. A smaller diameter gear 21 is also fixed onto counter shaft 26 and engages with an input gear 22. Power from motor shaft 4 is reduced in speed by gears 25, 24 and 21 to drive differential gear unit 23 by input gear 22. Larger diameter gear 24, on counter shaft 26, is disposed to the side of input gear 22 and overlaps in part therewith. Counter shaft 26 is rotatably housed in lower half housing 2 and is supported at both axial ends in a recess formed on the side wall of lower half housing 2 and a recess formed on the internal wall 2a of lower half housing 2, as shown in Fig. 2, so as to be rotatably supported when lower half housing 2 is joined with upper half housing 1.

[0036] As best seen in Figures 2 and 22, the distal ends of axles 7 are rotatably supported by ball bearings in axle housing portions projecting from upper half housing 1. The proximate end of each axles 7 is sleeved by a bearing bush. One half of each bearing bush is received in a recess in upper half housing 1. The other half is received by a projection of lower half housing 2 which enters into upper half housing 1. Axles 7 are rotatably supported to receive power transmitted through differential gear 23. As shown in Figure 2, the HST is disposed to the right side of the drive train. A control arm 38 for movable swash plate 11 is disposed to the right side of the HST. Hydraulic pump P is positioned substantially at the lateral and longitudinal center of the apparatus and is disposed so as to avoid the enlarged portion of differential gear 23. This enables the housing to be compact.

[0037] Differential gear unit 23 is shown in Figs. 22 through 25. As seen in Fig. 24, the center of input gear 22 has a shaft bore 22a for receiving axles 7 therein. Bores 22b for receiving differential pinions 80 and fitting-in bores 22a for receiving the differential locking device are disposed at both sides of input gear 22. Spline-fitted bevel-type output gears 81L and 81R are disposed at the proximate end of axles 7. Spindles 80a of the bevel-type differential pinions 80 are retained in bores 22b of input gear 22 in which differential pinions 80 are also housed. Differential pinions 80 engage with output gears 81L and 81R so as to form differential gear unit 23. No differential casing is otherwise provided. The differential locking device is provided opposite to the drive train at one side (preferably the right side) of differential gear 23 unit.

[0038] Between output gear 81R and the proximate end of right axle 7 is interposed a collar 83 on which a slider 82 is axially slidably fitted. Slider 82 is cup-like shaped to wrap around output gear 81R. At the outer peripheral side surface of slider 82, projections 82a are integrally provided. Projections 82a are permanently engageable with insertion bores 22c of input gear 22. At the inner peripheral side surface of slider 82 are formed a plurality of projections 82b which are engageable with a plurality of recesses 81 a formed in the outer periphery of output gear 81R. An insertion groove 82c is formed on the cylindrical portion of slider 82 opposite to projections 82a. so as to fit the tip of a fork 84 into groove 82. The base of fork 84 is slidably fitted onto a shaft 85 which is journalled to both side walls in lower half housing 2. At the side surface of the base of fork 84 is formed a cam surface 84a, which abuts against a pin 87 provided on shaft 85 so as to constitute a cam mechanism. An arm 86 is fixed to shaft 85. Arm 86 projects outwardly from the housing so as to connect with a differential locking pedal (not shown) provided on the vehicle.

[0039] In such construction, when the operator presses the differential locking pedal, shaft 85 rotates through arm 86, and pin 87 rotates to push to the right in the drawing of Fig. 22. As a result, cam surface 84a abuts against pin 87 so as to slidably move fork 84. At the same time, slider 82 slides, while maintaining projections 82a in insertion bores 22c of ring gear 22. Projections 82b engage with recesses 8 1a of output gear 81R and input gear 22 is differentially locked and coupled with axles 7. As a result, axles 7 are uniformly driven when the vehicle runs on any road surface.

[0040] The axle driving apparatus of the present invention can be used for driving the axles of a vehicle to improve the operability of changing the speed of the vehicle. An example of a moving vehicle which may utilize the above-mentioned axle driving apparatus is a farm or other working vehicle, such as a tractor with a mower attachment, or other vehicle for transportation.

[0041] While one embodiment of the present invention has been shown and described, the invention should not be limited to the specific construction thereof, and is meant to be merely exemplary.

Claims

1. An axle driving apparatus for a vehicle, including
   a housing (1,2) containing an axle (7),
   a hydrostatic transmission comprising an axial piston type variable displacement hydraulic pump (P) and a hydraulic motor (M) fluidly connected with each other,
   a drive train drivingly connecting an output means (4) driven by said hydraulic motor (M) with said axle (7), and
   an input means (3) driving said hydraulic pump (P) and being substantially perpendicular to a rotary axis of said axle (7),
   a movable swash plate (11) receiving thrust from heads of a plurality of pistons (12) reciprocatingly disposed in a cylinder block (16) of said hydraulic pump (P)
   said cylinder block (16) of said hydraulic pump (P) has a rotary axis which is substantially perpendicular to a rotary axis of said axle (7), characterized in that said swash plate (11) is rotatably supported in substantially parallel to said axle (7) in said housing by means disposed on opposite sides of saidswash plate (11) so that said movable swash plate (11) is slantingly rotated around an axis substantially parallel to said axle (7),
   said means for supporting said swash plate (11) comprise a trunnion (35R) projecting outwardly from said housing, and
   an arm (38) is fixed to the projecting portion of said trunnion so that said arm and a speed changing operating member equipped on a vehicle in connection with said arm are adapted to be rotated in a plane substantially perpendicular to said axle (7).

2. The axle driving apparatus for a vehicle according to claim 1, characterized in that a shock absorber (73) is interposed between said arm and a part of said housing outside said housing.

3. The axle driving apparatus for a vehicle according to claim 1, characterized in that said trunnion (35R) is supported through a side plate (15) covering an opening (1c) of Said housing and a biasing mechanism is interposed between said side plate and said movable swash plate (11) so as to bias said biasing mechanism toward its neutral position.

4. The axle driving apparatus for a vehicle according to claim 3, characterized in that a cooling fan (44) is provided on said input means projecting outside said housing and a plurality of fins (15a) are provided on said side plate (15) so as to be blown by said cooling fan (44).

5. The axle driving apparatus for a vehicle according to claim 1, characterized in that an internal wall (8) is provided in said housing and another opposite trunnion (35L) of said movable swash plate (11) is supported by said internal wall (8).

6. The axle driving apparatus for a vehicle according to claim 5, characterized in that said internal wall (8) divides the interior of said housing into a first chamber (R1) containing said hydrostatic transmission and a second chamber (R2) containing said drive train.

7. The axle driving apparatus for a vehicle according to claim 6, characterized in that a reservoir (10) is disposed outside said housing so as to be fluidly connected to said first chamber (R1) for absorbing excessive fluid increased in said first chamber (R1).

8. The axle driving apparatus for a vehicle according to claim 6 or 7, characterized in that a filter (18) is provided in an opening (8a) through said internal wall so as to allow fluid to flow therethrough between said first chamber (R1) and said second chamber (R2).

9. The axle driving apparatus for a vehicle according to claim 8, characterized in that a charge pump (45) is driven by said input means for feeding said hydrostatic transmission with fluid and another filter (56) is connected to an intake port of said charge pump so as to filtrate fluid in said first chamber (R1).

10. The axle driving apparatus for a vehicle according to claim 9, characterized in that said charge pump provided at its intake port with said other filter (56) is also used as a fluid takeout pump for supplying a hydraulic instrument disposed outside said housing with fluid from the interior of said housing.

11. The axle driving apparatus for a vehicle according to claim 5, characterized in that said housing comprises a first housing part (1) and a second housing part (2) joined along an imaginary plane which is substantially parallel to said axle and substantially perpendicular to said input means, and said movable swash plate (11) having said trunnions is provided in said first housing part (1), so that one of said trunnions projects outwardly from said first housing part (1) and the other thereof is supported by a first internal wall portion provided in said first housing part (1).

12. The axle driving apparatus for a vehicle according to claim 11, characterized in that a second internal wall portion (2a) is provided in said second housing part (2), so that said first internal wall portion and said second internal wall portion abut against each other along said imaginary plane when said first housing part (1) and said second housing part (2) are joined together, thereby dividing the interior of said housing into a first chamber (R1) containing said hydrostatic transmission and a second chamber (R2) containing said drive train.

13. The axle driving apparatus for a vehicle according to claim 12, characterized in that a shaft (26) is sandwiched between said first internal wall portion and said second internal wall portion so as to extend substantially in parallel to said axle, and an intermediate transmitting member (24,21) which is rotatable around said shaft (26) is interposed between said output means and said axle.

14. The axle driving apparatus for a vehicle according to claim 1, characterized in that said output means is substantially parallel to said axle and said drive train drivingly connects said output means with a differential gear unit (23) interposed between two co-axial axles.

15. The axle driving apparatus for a vehicle according to claim 14, characterized in that said differential gear unit is provided with clutch means, including an input gear (22) and a pair of output gears (81L,81R), interposed between said differential gear unit and one of said axles.

16. The axle driving apparatus for a vehicle according to claim 15, characterized in that a clutch slider (82) is rotatably and axially slidably provided on said one of axles.

17. The axle driving apparatus for a vehicle according to claim 16, characterized in that said clutch slider (82) includes a first engaging portion (82a), which permanently engages with said input gear regardless of a position of said clutch slider (82), and a second engaging portion (82b), which is adapted to engage with and disengage from one of said output gears integrally connected with said one of axles in accordance with the position of said clutch slider (82).

18. The axle driving apparatus for a vehicle according to claim 17, characterized in that a fork (84) engages with said clutch slider (82) and is slidably attached on an operating shaft (85) rotatably supported in said housing in substantially parallel to said axles, and a cam mechanism (84a,87) is provided between said connecting shaft and said fork (84) so as to be able to convert rotating motion of said operating shaft (85) into linear slide motion of said fork (84) on said operating shaft (85) so as to slide said clutch slider (82).

Ansprüche

1. Achsantriebsyorrichtung für. ein Fahrzeug mit
   einem Gehäuse (1,2), das eine Achse (7) enthält,
   einem hydrostatischen Getriebe mit einer Hydraulikpumpe (P) vom Axialkolbentyp mit variabler Verdrängung und einem Hydraulikmotor (M), die fluidmäßig miteinander verbunden sind,
   einem Getriebezug, der ein Ausgabemittel (4), das durch den Hydraulikmotor (M) angetrieben wird, mit der Achse (7) antriebsmäßig verbindet, und
   einem Eingabemittel (3), das die Hydraulikpumpe (P) antreibt und im wesentlichen senkrecht zu einer Drehachse der Achse (7) ist,
   einer beweglichen Taumelscheibe (11), welche Druck bzw. Schub von Köpfen von mehreren Kolben (12) aufnimmt, die hinund herbewegbar in einem Zylinderblock (16) der Hydraulikpumpe (P) angeordnet sind,
   wobei der Zylinderblock (16) der Hydraulikpumpe (P) eine Drehachse aufweist, die im wesentlichen senkrecht zu einer Drehachse der Achse (7) ist, dadurch gekennzeichnet, dass die Taumelscheibe (11) im wesentlichen parallel zu der Achse (7) in dem Gehäuse durch Mittel drehbar gelagert ist, die an gegenüberliegenden Seiten der Taumelscheibe (11) so angeordnet sind, dass die bewegliche Taumelscheibe (11) in Schrägstellung um eine im wesentlichen zur Achse (7) parallele Achse gedreht wird,
   das Mittel zum Lagern bzw. Haltern der Taumelscheibe (11) einen Lagerzapfen (35R) umfasst, der aus dem Gehäuse vorsteht, und
   ein Arm (38) an dem vorstehenden Abschnitt des Lagerzapfens so befestigt ist, dass der Arm und ein Geschwindigkeitswechselbetätigungselement, das an einem Fahrzeug in Verbindung mit dem Arm vorgesehen ist, sich in einer Ebene, die im wesentlichen senkrecht zu der Achse (7) ist, zu drehen vermögen.

2. Achsantriebsvorrichtung für ein Fahrzeug nach Anspruch 1, dadurch gekennzeichnet, dass ein Stoßdämpfer (73) zwischen den Arm und einen Teil des Gehäuses außerhalb des Gehäuses eingefügt ist.

3. Achsantriebsvorrichtung für ein Fahrzeug nach Anspruch 1, dadurch gekennzeichnet, dass der Lagerzapfen (35R) durch eine Seitenplatte (15) gehaltert ist, welche eine Öffnung (1c) des Gehäuses bedeckt, und ein Vorbelastungsmechanismus zwischen die Platte und die bewegliche Taumelscheibe (11) so eingefügt ist, dass sie den Vorbelastungsmechanismus zu seiner Neutralposition hin vorbelastet.

4. Achsantriebsvorrichtung für ein Fahrzeug nach Anspruch 3, dadurch gekennzeichnet, dass ein Kühlgebläse (44) an dem Eingabemittel vorgesehen ist, das aus dem Gehäuse vorsteht, und mehrere Rippen (15a) an der Platte (15) so vorgesehen sind, dass sie von dem Kühlgebläse (44) angeblasen werden.

5. Achsantriebsvorrichtung für ein Fahrzeug nach Anspruch 1, dadurch gekennzeichnet, dass eine Innenwand (8) in dem Gehäuse vorgesehen ist und ein weiterer gegenüberliegender Lagerzapfen (35L) der beweglichen Taumelscheibe (11) durch die Innenwand (8) gelagert bzw. gehaltert ist.

6. Achsantriebsvorrichtung für ein Fahrzeug nach Anspruch 5, dadurch gekennzeichnet, dass die Innenwand (8) das Innere des Gehäuses in eine das hydrostatische Getriebe enthaltende erste Kammer (R1) und eine den Getriebezug enthaltende zweite Kammer (R2) unterteilt.

7. Achsantriebsvorrichtung für ein Fahrzeug nach Anspruch 6, dadurch gekennzeichnet, dass ein Reservoir (10) außerhalb des Gehäuses so angeordnet ist, dass es in Fluidverbindung mit der ersten Kammer (R1) steht, um überschüssiges Fluid, das sich in der ersten Kammer (R1) angesammelt hat, aufzunehmen.

8. Achsantriebsvorrichtung für ein Fahrzeug nach Anspruch 6 oder 7, dadurch gekennzeichnet, dass ein Filter (18) in einer Öffnung (8a) durch die Innenwand so vorgesehen ist, dass es durch sich eine Fluidströmung zwischen der ersten Kammer (R1) und der zweiten Kammer (R2) gestattet.

9. Achsantriebsvorrichtung für ein Fahrzeug nach Anspruch 8, dadurch gekennzeichnet, dass eine Einsatz- bzw. Förderpumpe (45) durch das Eingabemittel zum Zuführen von Fluid zu dem hydrostatischen Getriebe angetrieben ist bzw. wird, und ein weiteres Filter (56) mit einer Einlassöffnung der Förderpumpe verbunden ist, so dass Fluid in der ersten Kammer (R1) gefiltert wird.

10. Achsantriebsvorrichtung für ein Fahrzeug nach Anspruch 9, dadurch gekennzeichnet, dass die an ihrer Einlassöffnung mit dem anderen Filter (56) versehene Förderpumpe auch als Fluid-Austragspumpe verwendet wird, um einem hydraulischen Instrument, das außerhalb des Gehäuses angeordnet ist, Fluid aus dem Innern des Gehäuses zuzuführen.

11. Achsantriebsvorrichtung für ein Fahrzeug nach Anspruch 5, dadurch gekennzeichnet, dass das Gehäuse einen ersten Gehäuseteil (1) und einen zweiten Gehäuseteil (2) umfasst, die entlang einer imaginären Ebene zusammengefügt sind, welche im wesentlichen parallel zu der Achse und im wesentlichen senkrecht zu dem Eingabemittel ist, und die bewegliche Taumelscheibe (11) mit den Lagerzapfen in dem ersten Gehäuseteil (1) so vorgesehen ist, dass einer der Lagerzapfen aus dem ersten Gehäuseteil (1) nach außen vorsteht und der andere derselben durch einen im ersten Gehäuseteil (1) vorgesehenen ersten Innenwandabschnitt gelagert bzw. gehaltert ist.

12. Achsantriebsvorrichtung für ein Fahrzeug nach Anspruch 11, dadurch gekennzeichnet, dass ein zweiter Innenwandabschnitt (2a) in dem zweiten Gehäuseteil (2) so vorgesehen ist, dass der erste Innenwandabschnitt und der zweite Innenwandabschnitt entlang der imaginären Ebene aneinanderliegen, wenn der erste Gehäuseteil (1) und der zweite Gehäuseteil (2) zusammengefügt sind, wodurch das Innere des Gehäuses in eine erste, das hydrostatische Getriebe enthaltende Kammer (R1) und eine zweite, den Getriebezug enthaltende Kammer (R2) unterteilt ist.

13. Achsantriebsvorrichtung für ein Fahrzeug nach Anspruch 12, dadurch gekennzeichnet, dass eine Welle (26) zwischen den ersten Innenwandabschnitt und den zweiten Innenwandabschnitt so eingefügt ist, dass sie sich im wesentlichen parallel zu der Achse erstreckt, und ein Zwischenübertragungselement (24,21), das um die Welle (26) drehbar ist, zwischen das Ausgabemittel und die Achse eingefügt ist.

14. Achsantriebsvorrichtung für ein Fahrzeug nach Anspruch 1, dadurch gekennzeichnet, dass das Ausgabemittel im wesentlichen parallel zu der Achse ist und der Getriebezug das Ausgabemittel mit einer Differentialgetriebeeinheit (23), die zwischen zwei koaxiale Achsen eingefügt ist, antriebsmäßig verbindet.

15. Achsantriebsvorrichtung für ein Fahrzeug nach Anspruch 14, dadurch gekennzeichnet, dass die Differentialgetriebeeinheit mit Kupplungsmitteln mit einem Eingangszahnrad (22) und einem Paar Ausgangszahnrädern (81L,81R) versehen ist, welche zwischen die Differentialgetriebeeinheit und eine der Achsen eingefügt sind.

16. Achsantriebsvorrichtung für ein Fahrzeug nach Anspruch 15, dadurch gekennzeichnet, dass ein Kupplungs-Gleitelement (82) drehbar und axial verschiebbar auf einer der Achsen vorgesehen ist.

17. Achsantriebsvorrichtung für ein Fahrzeug nach Anspruch 16, dadurch gekennzeichnet, dass das Kupplungs-Gleitelement (82) einen.ersten Eingriffsabschnitt (82a), der permanent mit dem Eingangszahnrad unabhängig von einer Position des Kupplungs-Gleitelements (82) in Eingriff steht, und einen zweiten Eingriffsabschnitt (82b), der mit einem der Ausgangszahnräder, das bzw. die integral mit der einen der Achsen verbunden ist/sind, gemäß der Position des Kupplungs-Gleitelements (82) in und außer Eingriff zu kommen vermag, aufweist.

18. Achsantriebsvorrichtung für ein Fahrzeug nach Anspruch 17, dadurch gekennzeichnet, dass eine Gabel (84) mit dem Kupplungs-Gleitelement (82) in Eingriff ist und gleitend bzw. verschiebbar an einer Betätigungswelle (85) angebracht ist, welche drehbar in dem Gehäuse im wesentlichen parallel zu den Achsen gelagert ist, und ein Nockenmechanismus (84a,87) zwischen der Verbindungswelle und der Gabel (84) so vorgesehen ist, dass er eine Drehbewegung der Betätigungswelle (85) in eine lineare Gleitbewegung der Gabel (84) auf der Betätigungswelle (85) umwandeln kann, um so das Kupplungs-Gleitelement (82) zu verschieben.

Revendications

1. Appareil de commande d'essieu pour un véhicule, comprenant :

un boîtier (1, 2) contenant un essieu (7)

une transmission hydrostatique comprenant une pompe hydraulique à cylindrée variable (P), de type à piston axial et un moteur hydraulique (M) relié fluidiquement entre l'un à l'autre,

un train d'entraînement reliant en entraînement des moyens de sortie (4) entraînés par ledit moteur électrique (M)"audit essieu (7), et

des moyens d'entrée (3) entraînant ladite pompe hydrauliques (P) et sensiblement perpendiculaire à l'axe de rotation dudit essieu (7),

une plaque de nutation (11) mobile recevant une poussée de la part des têtes d'une pluralité de pistons (12) disposés de façon à pouvoir effectuer un mouvement alternatif dans un bloc cylindre (16) de ladite pompe hydraulique (P)

ledit bloc cylindre (16) de ladite pompe hydraulique (P) comportant un axe de rotation sensiblement perpendiculaire à un axe de rotation dudit essieu (7),

caractérisé en ce que
   ladite plaque de nutation (11) est supportée à rotation sensiblement parallèlement audit essieu (7), dans ledit boîtier, par des moyens disposés sur des côtés opposés de ladite plaque de nutation (11), de manière que ladite plaque de nutation (11) mobile soit mise en rotation obliquement autour d'un axe sensiblement parallèlement audit essieu (7),
   lesdits moyens pour supporter ladite plaque de nutation (11) comprennent un tronçon (35R) faisant saillie extérieurement dudit boîtier, et
   un bras (38) est fixé à la partie en saillie dudit tronçon, de manière que ledit bras et un élément d'actionnement de changement de vitesse monté en équipement sur un véhicule, en liaison avec ledit bras, soïent adaptés pour être tourné dans un plan sensiblement perpendiculaire audit essieu (7).

2. Appareil de commande d'essieu pour un véhicule selon la revendication 1, caractérisé en ce qu'un amortisseur (73) est interposé entre ledit bras et une partie dudit boîtier extérieur audit boîtier.

3. Appareil de commande d'essieu pour un véhicule selon la revendication 1; caractérisé en ce que ledit tronçon (35R) est supporté par une plaque latérale (15) couvrant une ouverture (lc) dudit boîtier et un mécanisme de déplacement est interposé entre ladite plaque latérale et ladite plaque de nutation (11) mobile, de manière à faire passer ledit mécanisme de déplacement à sa position neutre.

4. Appareil de commande d'essieu pour un véhicule selon la revendication 3, caractérisé en ce qu'un ventilateur de refroidissement (44) est prévu sur lesdits moyens d'entrée, en saillie à l'extérieur dudit boîtier et une pluralité d'ailettes (15a) sont prévues sur ladite plaque latérale (15) pour être soumis au soufflage dudit ventilateur de refroidissement (44).

5. Appareil de commande d'essieu pour un véhicule selon la revendication 1, caractérisé en ce qu'une paroi interne (8) est prévue dans ledit boîtier et un autre tronçon (35L) opposé de ladite plaque de nutation (11) mobile est supportée part ladite paroi interne (8).

6. Appareil de commande d'essieu pour un véhicule selon la revendication 5, caractérisé en ce que ladite paroi interne (8) divise l'intérieur dudit boîtier en une première chambre (R1) contenant ladite transmission hydrostatique, et une deuxième chambre (R2) contenant ledit train d'entraînement.

7. Appareil de commande d'essieu pour un véhicule selon la revendication 6, caractérisé en ce qu'un réservoir (10) est disposé à l'extérieur dudit boîtier pour être relié fluidiquement à ladite première chambre (R1) pour absorber un excès de fluide se manifestant dans ladite première chambre (R1).

8. Appareil de commande d'essieu pour un véhicule selon la revendication 6 ou 7, caractérisé en ce qu'un filtre (18) est prévu dans une ouverture (8a), traversant ladite paroi interne pour permettre à du fluide de s'écouler à travers lui entre ladite première chambre (R1) et ladite deuxième chambre (R2).

9. Appareil de commande d'essieu pour un véhicule selon la revendication 8, caractérisé en ce qu'une pompe de charge (45) est entraînée par lesdits moyens d'entrée pour alimenter ladite transmission hydrostatique par du fluide et un autre filtre (56) est connecté à un port d'admission de ladite pompe de charge pour filtrer du fluide dans ladite première chambre (R1) .

10. Appareil de commande d'essieu pour un véhicule selon la revendication 9, caractérisé en ce que ladite pompe de charge, munie à son orifice d'admission dudit autre filtre (56) est également utilisée comme pompe de prélèvement pour alimenter un instrument hydraulique disposé à l'extérieur dudit boîtier en fluide provenant de l'intérieur dudit boîtier.

11. Appareil de commande d'essieu pour un véhiculeselon la revendication 5, caractérisé en ce que ledit boîtier comprend une première partie de boîtier (1) et une deuxième partie de boîtier (2) reliées dans un plan imaginaire sensiblement parallèle audit essieu et sensiblement perpendiculaire auxdits moyens d'entrée, et de ladite plaque de nutation (11) mobile présentant lesdits tronçons est prévue, dans ladite première partie de boîtier (1), de manière que l'un desdits tronçons fasse saillie extérieurement de ladite première partie de boîtier (1) et que l'autre soit supportée par une première partie de paroi interne, prévue dans ladite première partie de boîtier (1).

12. Appareil de commande d'essieu pour un véhicule selon la revendication 11, caractérisé en ce qu'une deuxième partie de boîtier interne (2a) est prévue dans ladite deuxième partie de boîtier (2), de manière que ladite première partie de paroi interne et ladite deuxième partie de paroi interne, butent l'une contre l'autre dans ledit plan imaginaire lorsque ladite première partie de boîtier (1) et ladite deuxième partie de boîtier (2) sont reliées ensemble, de manière à diviser l'intérieur dudit boîtier en une première chambre (R1) contenant ladite transmission hydrostatique et une deuxième chambre (R2) contenant ledit train d'entraînement.

13. Appareil de commande d'essieu pour un véhicule selon la revendication 12, caractérisé en ce qu'un arbre (26) est interposé entre ladite première partie de paroi interne et ladite deuxième partie de paroi interne, de manière à s'étendre sensiblement parallèlement audit essieu, et un organe de transmission intermédiaire (24, 21), susceptible de tourner autour dudit arbre (26), est interposé entre lesdits moyens de sortie et ledit essieu.

14. Appareil de commande d'essieu pour un véhicule selon la revendication 1, caractérisé en ce que lesdits moyens de sortie sont sensiblement parallèles audit essieu et ledit train d'entraînement relie en entraînement lesdits moyens de sortie à une unité d'engrenage différentielle (23) interposée entre deux essieux coaxiaux.

15. Appareil de commande d'essieu pour un véhicule selon la revendication 14, caractérisé en ce que ladite unité d'engrenage différentielle est munie de moyens d'embrayage, incluant une roue dentée d'entrée (22) et une paire de roues dentées de sortie (81L, 81R), interposées entre ladite unité d'engrenage différentielle et l'un desdits essieux.

16. Appareil de commande d'essieu pour un véhicule selon la revendication 15, caractérisé en ce qu'un coulisseau d'embrayage (82) est monté de façon à pouvoir tourner et à pouvoir coulisser axialement sur l'un desdits essieux.

17. Appareil de commande d'essieu pour un véhicule
   selon la revendication 16, caractérisé en ce que ledit coulisseau d'embrayage (82) comprend une première partie de mise en prise (82a) venant en prisé en permanence avec ladite roue dentée d'entrée, indépendamment de la position dudit coulisseau d'embrayage (82) et une deuxième partie de mise en prise (82b), adaptée pour venir en prise et hors de prise . vis-à-vis d'une desdites roues dentées de sortie, reliées solidairement audit un des éssieux selon la position dudit coulisseau d'embrayage (82).

18. Appareil de commande d'essieu pour un véhicule selon la revendication 17, caractérisé en ce qu'une fourche (84) vient en prise avec ledit coulisseau d'embrayage (82), et est fixée de façon coulissante sur un arbre d'actionnement (85) monté à rotation dans ledit boîtier, sensiblement parallèlement auxdits essieux, et un mécanisme à came (84a, 87) est prévu entre ledit arbre de connexion et ladite fourche (84) pour être en mesure de convertir le mouvement rotatif dudit arbre d'actionnement (85) en un mouvement coulissant linéaire de ladite fourche (84) sur ledit arbre d'actionnement (85) de manière à faire coulisser ledit coulisseau d'embrayage (82).

Drawing